This invention is concerned with efficient mixing of liquids and slurries using a reciprocating motion to oscillate a mixing disk. In particular the invention is directed to increasing mixing performance and efficiency with optimized geometry in a mixing disk in a reciprocating mixer. An important application of the invention is in wastewater treatment, in the mixing of wastewater slurries, especially in digesters, such as anaerobic digesters.
Linear motion mixers, i.e. reciprocating motion mixers, are described in U.S. Pat. Nos. 7,685,896, 7,399,112, 7,364,351, 7,278,781, 7,029,166, 6,830,369, 6,007,237, 5,100,242 and 5,052,813, as well as U.S. Pub. No. 2015/182927. These mixers, at least in the context of the current invention, typically are used in very large vessels, such as, for example, a mixing disk of six feet operating in a vessel about 50 feet in diameter. The vessel or tank can be much larger.
As discussed in some of the above patents and publication, several recognize the mixing disk geometry as having an effect on the efficiency and performance of the reciprocating mixer disk. Some of the patents, such as U.S. Pat. Nos. 6,830,369 and 7,685,896, provide a formula for a target range of effectiveness, the formula including, effectively, the ratio of the overall circular area defined by the entire disk to the open area at the center of the disk, wherein stroke length and cycle duration are also considered in the formula.